What follows is a taxonomy of arguments that regresses of inferential justification are vicious. They fall out into four general classes: (A) conceptual arguments from incompleteness, (B) conceptual arguments from arbitrariness, (C) ought-implies-can arguments from human quantitative incapacities, and (D) ought-implies can arguments from human qualitative incapacities. They fail with a developed theory of “infinitism” consistent with valuational pluralism and modest epistemic foundationalism